/Engine/Plugins/Online/OnlineSubsystem/Source/Public/Interfaces/OnlineMessageInterface.h
virtual [FDelegateHandle](API\Runtime\Core\Delegates\FDelegateHandle) AddOnReadMessageCompleteDelegate_Handle ( int32 LocalUserNum, const [FOnReadMessageCompleteDelegate](API\Plugins\OnlineSubsystem\Interfaces\FOnReadMessageCompleteDelegate) & Delegate )